Chickamin Glacier covers the north slope of Sinister Peak in the North Cascade Range of Washington. The glacier has a valley tongue that descends to an outwash plain. Here we examine retreat of the glacier from 1979 to 2012. The glacier had advanced from 1955-1975, before commencing retreat.
Chickamin Glacier (Tom Hammond)
USGS Map of Chickamin Glacier
In 1979 the glacier terminus was at the pink arrow, several hundred meters beyond a prominent buttress, red arrow, where the glacier turns west. The lowest icefall is indicated by a green arrow. In 1991 the glacier has retreated from the pink arrow, but still is turning the corner beyond the buttress. The lower icefall is still extensively crevassed. By 1998 in a Google Earth image the terminus is outlined with yellow dots and has retreated 230 m from the 1979 position. The lower icefall is still crevassed. By 2005 in a photograph from Tom Hammond (North Cascades Conservation Council), the glacier has retreated to the buttress. in a 2006 Google Earth image the terminus position is indicated by yellow dots, with a retreat of 50 m since 1998. The lower portion of the glacier has limited crevassing. In the 2012 image the glacier terminus no longer reaches the buttress and has retreated 360 m since 1979. We observed exceptional ablation conditions in the North Cascades in 2013 and 2014, which combined with exceptionally low snowpack in 2015 will lead to a continued significant retreat of this glacier. The crevassing in the lowest icefall has declined and is now superficial. All 47 glaciers observed by the North Cascade Glacier Climate Project have been retreating and four have disappeared (Pelto, 2011). This glacier is similar in size and retreat to Boston Glacier and Honeycomb Glacier.
Chickamin Glacier 1979 (Austin Post)
1991 Chickamin Glacier
1998 Google Earth image
2005 Chickamin Glacier (Tom Hammond)
2006 Google Earth image
2012 Google Earth Image
Eiriksjökull is an ice cap just west of Langjökull In central Iceland. Here we examine its main western outlet the Braekur using Landsat imagery from 1989 to 2014. The Icelandic Glaciological Society website on terminus variations is the source of the map for the glacier. The IGS program monitors 50 glaciers, all of them are currently retreating. Eiriksjökull , is not one that is in this monitoring program.
In 1989 the Braekur outlet flowed over the edge of a lava cliff at the red arrow. The glacier terminated on the bench between the upper and lower cliff. In 1994 the glacier still extended to the edge of the cliff. By 2010 the Google Earth images indicates a retreat from the edge of the cliff. In 2014 the glacier has receded 200 m from the edge of the cliff and 300 m from is 1989 position and terminates at the yellow arrow. The high snowlines in recent years will lead to continued retreat. The retreat and area loss of Eiriksjökull is less than on nearby Norðurjökull a primary outlet of Langjökull or on Porisjokull a small ice cap just south of Langjökull.
1989 Landsat image
1994 Landsat image
2010 Google Earth image
2014 Landsat image
Weddel Glacier is on the southeast coast of South Georgia Island. It terminates in Beaufoy Cove just north of Gold Harbor.The change in glacier terminus position has been documented by Alison Cook at British Antarctic Survey in a BAS retreat map. In 1958 it reached within 400 m of the coast at the outlet of Beaufoy Cove. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. For Weddel Glacier the retreat was rapid from 1960 to 1974 and was slow from 1992-2003. Here we examine Landsat imagery from 1989 to 2015 to visualize and update this change.
Google Earth Image
BAS map of glacier terminus position
In 1989 the glacier terminates near the tip of a peninsula, red arrow in each image. The calving front extends southeast, orange dots. At the yellow arrow the glacier fills a small side valley adjacent to the main glacier. At the purple arrow is a small extension of the main icefall flowing down the bedrock step.
In 2002 there is only minor retreat at the red and yellow arrow, but thinning has led to the small extension of the main icefall being almost cutoff by bedrock. By 2015 the glacier has retreated 200-300 meters from the 1989 position and the main terminus is narrower. At the yellow arrow the side valley no longer has ice. At the purple arrow this is just bedrock now, there is no glacier extension flowing down the bedrock step. A close up the icefall in a 2009 Google Earth image indicates both the extensive crevassing but also the lack of glacier ice at the purple arrow, where an extension of the icefall formerly flowed. A Google Earth closeup of the terminus indicates that only a small section is still in contact with Beaufoy Cove in 2009, with land exposed at the orange arrows. This glacier is almost not tidewater and has terminated in shallow water since 1989, which helps explain a slower rate of retreat. The glacier has thinned more rapidly than it has retreated in the last 25 years. The retreat rate is less than nearby Bertrab Glacier, Konig Glacier and Neumayer Glacier on the same coast of South Georgia.
Landsat Image 1989
Landsat image 2002
Landsat image 2015
Google Earth icefall image
Google Earth 2009 image
Bertrab Glacier is on the east coast of South Georgia Island. The change in glacier terminus position has been documented by Alison Cook at British Antarctic Survey in a BAS retreat map. In 1958 it reached the coast in Gold Harbor. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. For Bertrab Glacier the retreat was minimal from 1958 to 1989. Since 1989 a whole new embayment has opened. Here we examine Landsat imagery from 1989 to 2015 to visualize and update this change.
BAS Glacier Front map 1958-2007.
Google Earth image
In 1989 the southern arm of the glacier extends to the shoreline of the barrier beach system in Gold harbor, Red arrow. The northern arm extends around to the edge of a very green region, suggesting well developed vegetation, hence no real retreat for sometime. By 2002 a lake has formed at the northern arm terminus and it has retreated 400 m. The southern arm has retreated across a new embayment ending near the yellow arrow, though the exact position is obscured by cloud. In 2011 the southern terminus has retreated up a slope from the edge of the embayment, yellow arrow. In 2015 there are no longer two arms to the glacier. The glacier terminates near the edge of the new embayment. The retreat is 700 m on the northern arm and 1000 m for the southern end since 1989. The glacier no longer reaches the water limiting calving. The glacier also ends on moderate slope. This should lead to a reduced retreat in the near future. The 2015 picture is from Jan.15, so there is still two months left in the melt season. The retreat is similar to that of Ross Hindle Glacier , Konig Glacier and Neumayer Glacier on the same coast of South Georgia, and faster than for neighboring Weddel Glacier. Like on Stephenson Glacier, Heard Island the new embayment does offer new potential habitat for penguins and seals.
1989 Landsat image
2002 Landsat image
2011 Landsat image
2015 landsat image
The Brazeau Icefield straddles high peaks southeast of Jasper, Alberta. The northern outlet glaciers drain into Maligne Lake and the southern outlet glaciers drain in to Brazeau Lake and the Brazeau River. The Brazeau River flows into Brazeau Reservoir a 355 MW hydropower facility, before joining the Saskatchewan River. An inventory of glaciers in the Canadian Rockies indicate area loss of 15% from 1985 to 2005 (Bolch et al, 2010). The more famous Columbia Icefield to the west has lost 23 % of its area from 1919-2009 with ice loss at a minimum during the 1970’s (Tennant and Menounos, 2013). Here we examine an unnamed outlet glacier at the southwest corner of the Brazeau Icefield from 1995 to 2014 using Landsat imagery.
In 1995 the glacier terminated at the red arrow and was 1900 m long, orange dots mark the upper boundary. The glacier had limited retained snowpack in 1995. The poor clarity is do to forest fire smoke in the region. In 1998 the proglacial lake where the glacier terminates is much clearer, snowpack is again limited, but more extensive than in 1995. In 2002 retreat is evident as the lake is expanding as the glacier retreats. The glacier still ends in the lake and still has limited snowcover. In 2013 the glacier has retreated completely from the lake and snowcover is again limited. The lack of snowcover is persistent in the satellite images which are typically not from the end of the melt season, hence even more snowcover will be lost. Lack of a significant persistent snowcover area indicates a glacier that will not survive (Pelto, 2010). In 2014 the area experienced considerable forest fires, which leads to poor image clarity. The glacier terminus is now significantly separated from the lake and terminates at the yellow arrow. The distance from the yellow to the red arrow represents a 350-400 m retreat in 20 years. The glacier has lost 20% of its length in this period. This retreat is similar to that of Fraser Glacier and more significant given the small size of the glacier than for Saskcatchewan Glacier
1995 Landsat image
1998 Landsat image
2002 Landsat image
2013 Landsat image
2014 Landsat image
Almer Glacier is fed by the Salisbury Snowfield which also has its own terminus, and both are former tributaries to the Franz Josef Glacier. In 2007 the Almer Glacier almost reconnected with Franz Josef Glacier. The glaciers of the southern Alps have some of the highest recorded accumulation rates in their upper sections and highest ablation in the lower reaches. Anderson et al (2006), note accumulation rates exceeding 6 m on Franz Josef Glacier. This combined with the steep slopes lead to higher velocity and extensive crevassing on even smaller alpine glaciers. Purdie et al (2014) examined modern and historic length change for Franz Josef and noted a ~ 3 km loss in length since the 1800s, with the greatest retreat from 1934 and 1983, despite two periods of advance in that 50 year period. The retreat particularly since 1983 has been punctuated by advances 1983–1999 (1420 m) and 2004–2008 (280 m), with the current retreat up to 2014 being the fastest rate of retreat during the period of record. (Purdie et al , 2014). The annual end of summer snowline surveys by NIWA monitors the Salisbury Snowfield, the snowline was 140 m or more above the equilibrium altitude in 4 of the last six years and 20-30 m below the equilibrium line altitude in the other two. The net result is significant mass loss in the last six years driven by exceptional melt, driving the retreat.
Topographic Map of Salisbury Snowfield-Almer Glacier area
Here we examine changes particularly in crevassing as well as retreat of Salisbury Snowfield and Almer Glacier from 2000-2015. In the Google Earth images from 2007 and 2013 the green arrows indicate crevassed areas and the red arrows the terminus of the Almer Glacier above and Salisbury Snowfield below. The decrease in the amount of crevassing is evident at each location. This indicates not just a reduction in velocity, but in glacier thickness that is driving flow. The thinning is evident with the emergence of a bedrock knob at the pink arrow in 2013 that had been covered by crevassed ice in 2007. The red arrow indicates the terminus where the main Almer Glacier is within 75 m of the Franz Josef Glacier. By 2013 the terminus is much dirtier and is 200 m from Franz Josef Glacier. The icefall comparison image from 2007 and 2013 indicates the reduction in width and number of open crevasses, probably in depth too. This is something Jill Pelto (UMaine) has been measuring crevasses in the field on Easton Glacier in the North Cascades over the last few years to see how crevasses are changing as a glacier thins and slows (image below).
In 2014 New Zealand had a warm year and snowlines are high for early summer in January 2015 which will continue the retreat. The Landsat image from January, 2015 suggests further retreat has occurred since 2013, but given the dirty terminus, it is to hard to determine a specific amount. The retreat here follows the pattern of glaciers across the Southern Alps of New Zealand- Lyell Glacier and Tasman Glacier
2007 Google Earth image
2013 Google Earth Image.
2007-2013 icefall closeup
2015 Crevasse Assessment, Jill Pelto, North Cascades
2000 Landsat image
2015 Landsat image
Lys Glacier drains south from Lyskamm in the Monta Rosa Group of Italy. This glacier has a long history of observations that have indicated two short term advances in the 20th century 1912-21 and 1973-85 amidst a broader retreat. The net change for the 1915-2004 interval was a 600 meter retreat (Smiraglia et al, 2006). They also noted a 10% area extent loss from 1975-2003, and since the glacier was advancing up to 1985 this change occurred more rapidly. The Italian Glacier Commission report on terminus change of this glacier annually in the two latest reports Lys Glacier retreated 10 m in 2012 and 20 m in 2011. The total reported retreat from 2005-2012 was 186 m, more than 20 m per year. Here we examine Landsat images from 1990 to 2014.
Google Earth Image
In 1990 two branches of the glacier merged in the valley bottom and extended to the red arrow marking the terminus of the glacier at that time. The yellow arrow indicates the 2014 terminus position, and the yellow A indicates a prominent bedrock knob that a branch of the glacier encircles, pink arrows. By 2013 the glacier in the main valley have separated, there are a few small lakes forming amidst the decaying stagnant ice tongue between the yellow and red arrow. The bedrock knob at Point A has greatly expanded. In 2014 none of the termini reach the floor of the main valley. As the stagnant ice melts, the lake area is expanding indicating that a new alpine lake will likely form. The retreat from 1990-2014 is 1300 meters. A closeup in 2009 from Google Earth indicates the two tongues with bedrock below separating them from the main valley floor, red arrows. There is still some relict ice below on the valley floor detached from the active glacier, blue arrows, that has small lake developing amid the stagnant ice. There is substantial crevassing above both actual termini, but not immediately. The retreat should slow now that the glacier has retreated onto steeper slopes, having lost the low elevation low slope valley tongue.
The retreat of this glacier is similar to that of nearby Verra Grande Glacier.
1990 landsat image
2013 Landsat image
2014 Landsat Image
Google Earth Image